1. Field of the Invention
The invention relates generally to a rolling bearing unit, and more specifically to a rolling bearing unit that includes a sealing device.
2. Description of Related Art
A rolling bearing unit that includes a sealing device is used as a bearing unit that is used in an environment in which water is likely to enter the bearing unit from the outside, such as a bearing unit for a wheel of a vehicle. As such a rolling bearing unit that includes a sealing device, Japanese Patent Application Publication No. 2007-177814 (JP 2007-177814 A) describes a rolling bearing unit that includes an outer ring, an inner ring, a plurality of rolling elements, and a sealing device that is disposed at at least one of a position between one end portion of the outer ring and one end portion of the inner ring, and a position between the other end portion of the outer ring and the other end portion of the inner ring. The sealing device described in JP 2007-177814 A includes a metal core and an elastic seal. The metal core has a cylindrical portion that is fitted to an outer periphery of the outer ring. The elastic seal is fitted to the metal core.
In the rolling bearing unit described in JP 2007-177814 A, the cylindrical portion of the metal core is fitted to the outer ring by interference fit to prevent entry of water into the rolling bearing unit through a joint between the cylindrical portion and the metal core. However, the metal core is formed by press working, and therefore the accuracy of the metal core is not sufficiently high. Therefore, when the cylindrical portion is fitted to the outer ring, the cylindrical portion may flare out at its end portion and the end portion may be apart from the metal core. In this case, the waterproof property at the joint is reduced.